This invention relates to a data acquisition system which has a plurality of remote data gathering devices each of which communicates according to a respective defined communications protocol and, more particularly, to a data storage and management system for use in such a data acquisition system.
Today's utilities have new and ever increasing demands being placed on their information systems. Deregulation, increasing customer service demands, improving efficiencies (such as "unaccounted for gas"), improving management of customer demand (such as load balancing) and downsizing pressures, force the utilities to find more efficient ways of collecting and managing their data in order to compete. These factors exponentially increase the need for timely and accurate operational data. Additionally, new Information Superhighway technologies are opening up a vast information resource between utilities and their customers.
Some of the system requirements becoming important to utilities include integration of existing information systems, use of open systems standards, communications with a multitude of devices, lower system installation and operating costs, scalability for future growth, and ease of use. These requirements also create a new set of challenges, such as databases which can maintain large historical and configuration information on hundreds or even thousands of devices, maintaining and implementing both proprietary and new device protocol standards, and applying open systems technologies to create integrated information systems.
A utility's information systems can be generally divided into the following categories:
Automated Mapping/Facilities Management (AM/FM); PA1 Geographical Information System (GIS); PA1 Electronic Measurement/Supervisory Control and Data Acquisition (EM/SCADA); and PA1 Customer Information Systems/Financial Information Systems (CIS/FIS). PA1 Scalable, high-performance historical and configuration databases; PA1 Highly distributed architecture; PA1 Flexible communications systems; PA1 Management of multi-vendor devices; PA1 Open protocol development with support of smart devices (distributed intelligence); PA1 Dynamic, easy to use graphical user interfaces; PA1 Integrates easily with other information systems; PA1 Uses advanced PC operating systems in place of traditional mainframes and minicomputers; and PA1 Incorporates characteristics of both traditional EM and SCADA systems.
Utilities have invested vast amounts of money to develop these information systems and cannot afford to "start over". However, the new demands, as previously discussed, create an urgent need for cost effective technology that can utilize most of the prior information systems investments.
These requirements and challenges have generated a demand for new technology that integrates a utility's information sources and combines the strengths of both Electronic Measurement (EM) and Supervisory Control and Data Acquisition (SCADA) systems, while minimizing the weaknesses and limitations of each. A new technology emerging as a result of recent hardware and software advancements is being referred to as Distribution Automation (DA). DA synergizes the functionality, features, and characteristics of traditional EM and SCADA systems to provide a comprehensive automation and data management solution for local distribution utilities. Some of the characteristics of a DA system include:
The Information Superhighway (Iway) represents another driving factor for this new generation of Distribution Automation. The Iway is not just having a connection to the Internet. Several Iway type applications are currently in development which affect utility companies, including: direct access to customers for utilities through broadband networks, and consolidated energy management systems controlled by marketing companies with buying power. The new opportunities and demands opened up by Iway technologies actually obsolete many (if not all) traditional EM and SCADA systems. An Iway system is not just another meter reading technology; it is a wide open two-way communications link between utilities and their customers, creating a whole new world of business opportunities. Iway systems represent the most sophisticated use of Distribution Automation. The demands of an Iway system emphasize the characteristics and capabilities of Distribution Automation.
The growing use of Electronic Correctors has expanded the definition of a distributed system. Electronic Correctors provide true distributed intelligence, with local logic, historical, and auditing information at each site. A system comprised of several hundred or even a few thousand of these devices creates a tremendous logistical problem to deal with. The central host which maintains these devices must be able to manage each device's configuration data and bring back each device's historical and auditing information into a globally coherent database system, regardless of the type of device used in the field. It is then common for the utility to require at least a couple of years of on-line historical data (perhaps even to one-hour intervals) for all of the devices. System performance must also be maintained at all times for both user access and incoming data.
The value of the data obtained by a DA system can especially be realized if it can be exchanged with other information systems throughout the utility. For example, the Customer and Financial Information systems need accurate billing and usage data, and Facilities Management needs operational data. Open systems standards such as SQL (Structured Query Language) and ODBC (Microsoft Open Database Connectivity) are the basis for easy data exchange among diverse systems.
In order to minimize the cost of acquisition and maintenance while not jeopardizing the security of supply, utilities prefer to be able to purchase hardware, software, electronic measurement, RTUs and other SCADA devices from diverse manufacturers. Some devices are also better at certain functions than at others. However, despite the promise of protocol standards, there are a number of proprietary and "de-facto" standard protocols used throughout the industry. This diversity in communications makes the goal of mixing multi-vendor equipment difficult for the utility. There are systems on the market which support multiple protocols, however, this is usually at a penalty of reduced functionality. Traditional SCADA systems usually do not even provide a mechanism in their protocol systems to support intelligent devices which have their own configuration, auditing, and historical data. The results of many of the current protocol standards committees will produce new protocol implementations which are more robust than the traditional host systems have been designed to handle. These aspects prompt the need for a more robust open protocol development environment which supports easier integration of device protocols, including "smart" devices which support true distributed processing.
The demands of a DA system which have been discussed thus far would have traditionally prompted the use of a mainframe or minicomputer system. The nature of a DA system requires a tremendous amount of asynchronous activity, such as highly active communications and database systems. This type of computing can now be accomplished through the Client/Server architecture supported by newer operating systems such as NT, OS/2, and traditional UNIX. Operating systems like NT and OS/2 provide many of the advanced capabilities previously found only in UNIX and mainframe operating systems, but at a significantly lower cost to develop and maintain than the traditional systems. A DA system can now, therefore, be made affordable for the common Local Distribution Company (LDC), where previously only the large pipeline and LDC utilities could afford the expensive custom system solutions. The Client/Server technique also allows a system to be highly scalable to fit diverse needs. A network of personal computers running database and communication servers potentially has more computing and throughput power than an expensive mainframe system.
By incorporating characteristics found in traditional EM and SCADA systems, a DA system now has the edge to be used in diverse installations, where a mix of systems was previously required. Common components and features of a DA system sound like comparable EM and SCADA features: SQL database, communications server, protocol tool kit, object oriented Graphical User Interface, "real-time" database, historical data management, configuration management, recalculation of historical data, auditing, security, alarming, process graphics, trending, device management, etc. The big difference here is that these features and components should be closely integrated into a complete system to duplicate common EM and SCADA features while adding support for the new DA characteristics.
To better clarify how a DA system is different from traditional EM and SCADA systems, a discussion of EM and SCADA limitations is necessary. Considering the demands and challenges presented thus far, a number of problems arise in traditional EM and SCADA systems. SCADA systems are most noted for their fancy graphical user interfaces. However, the underlying architecture of SCADA often gets overshadowed by this pretty face. SCADA systems are typically based on a "real-time" database (RTDB) configured by points. Many SCADA systems have been designed for the factory floor, which would have a relatively small number of points as compared to the logistically large point counts required in a DA system. For example, a DA system with 500 devices and 25 operational parameters at each device requires 12,500 points. If each device can store 10,000 historical records (not uncommon), then the host system needs to support a minimum of 5 million rows of historical data (and more since the host would normally maintain more historical data than the remote devices). The math is easy, but this simple example is overwhelming for a SCADA system which is sold by the number of points. SCADA packages are presently not designed to easily manage or configure such a point count, which requires individual tag names and room in the memory based "real-time" database.
Protocol development in present SCADA packages also does not provide for the tremendous amount of historical and auditing data which can be generated by smart devices such as electronic correctors. SCADA packages offer access to diverse database engines. However, this is merely a cliff-hanger, since a database design for all of this data must be accomplished to meet the performance and storage needs of the system. This technique allows for a totally unique system for every utility, which translates to support headaches for both the utility and the system integrator. Again, much of this problem comes from the fact that many presently available SCADA systems primarily have focused on drawing tools and not the data management side of a system. Common SCADA packages on the market today are, essentially, a set of development tools. The idea of a DA system is to go beyond a set of development tools to provide a more robust environment ready to deal with the challenges we have presented here, much like the Microsoft Office suite is designed to incorporate solutions for common business applications. Some of the advantages a DA system borrows from a SCADA system include alarm handling, advanced graphics and control capabilities.
EM systems focus primarily on providing consumption data for billing purposes. Some of the characteristics of an EM system which would be considered as limitations in a DA system include: a focus primarily on read-only data translation; lack of device specific configuration capabilities; lack of modern object oriented graphics; lack of two-way capabilities if a low-end control site were to be used (such as a nomination control site); some older designs are not as scalable as the newer open systems designs; limitations on protocol development; and limited database storage capabilities. A DA system corrects these limitations while borrowing some EM system advantages such as historical recalculations, data validation, security and audit trails.
A properly designed DA system can take advantage of many proven technologies to provide an even more robust solution for the utility. For example, a properly selected client/server database system will provide full transaction processing for multiple users, automatic database recovery, on-line database backup, roll forward recovery, and scalability to manage hundreds or thousands of devices with several years of historical data without performance degradation.
A DA communications system should take advantage of ISO/OSI (International Standards Organization/Open Systems Interconnection) standards to allow open development of protocol drivers. By using the ISO/OSI standards, multiple protocols and media can be easily maintained in the system without modifying the DA system's architecture. Following these guidelines will also allow easier inclusion of more sophisticated protocols which are currently being defined by diverse standards committees (such as AGA, IEEE/AMRA SCC31, MMS Forum, IEA-60 Home Automation, and joint AMRA/ANSI/CCAC/IEEE working group on meter protocol). These protocols will have better support of the distributed systems architecture becoming prevalent through the use of "smart" devices (such as electronic correctors).
A DA system should incorporate advanced graphics and drag-and-drop techniques to make system management easier. Managing hundreds or thousands of devices (each with their own historical data, audit trails, alarms, configuration parameters, and other items) represents a significant data presentation challenge. Advanced dynamic object oriented graphics can be used to represent this data in the form of nested folders, tables, and notebooks (similar to OS/2's, the Mac's, and Win 95's object oriented user interfaces).
It is therefore a primary object of the present invention to provide a data acquisition system satisfying the foregoing requirements.
It is a more specific object of the present invention to provide a data storage and management system for such a data acquisition system so that data collected from remote data gathering devices can be stored in an efficient manner in a database which is expandable and scalable.